Hölzel et al – Mindfulness & Brain Scans

Psychology being Investigated

• Localisation of function: refers to the way particular brain areas are responsible for particular information processing or for specific activities [Main area studied here: hippocampus, responsible for memory, navigation and controlling emotions].

• Mindfulness: state achieved through meditation that aims to increase awareness of the present-moment experience and enable a person to look at themselves in a compassionate, non-judgmental way.

Background of the Study

• Mindfulness involves cognitive processes and sensory experiences that impact brain function.

• Early studies used EEG, but now MRI provides more detailed information by measuring brain structures and changes in grey and white matter.

• Comparative studies suggest differences in brain grey matter between individuals practising mindfulness meditation and those who don’t. However, caution is needed due to potential pre-existing individual differences that could affect results.

Aim of the Study

• To identify if regular participation in Mindfulness-Based Stress Reduction (MBSR) leads to measurable neurological changes, which might be associated with trait changes related to mindfulness practice.

• To identify brain structures which changed as a result of an eight-week MBSR programme.

Sample

• Opportunity sample – from four MBSR courses at Centre for Mindfulness, New England, USA.

• 33 right-handed, healthy adults, aged 25-55 years old.

• MBSR group – six males and ten females (mean age = 38, standard deviation = 4 years), Control group, from waitlist – eleven males and six females (mean age = 39, standard deviation = 9.2)

Research Method and Design

• Independent measures design

• Longitudinal study - data collected over an eight week period. Participants provided data at the beginning and end of the eight week period.

• Experiment - Lab experiment

• Independent Variables

  • Whether participants had done MBSR or not

  • Whether the data was collected at the beginning or the end of the eight-week study period.

• Dependent Variables

  • Grey matter concentration in specific brain structures (including the hippocampi and insulae) and throughout the brain - this was calculated using voxel-based morphometry.

  • The five facets of mindfulness measured in the questionnaire (FFMQ) – includes 39 statements which participants rate from 1 (‘never or very rarely true’) to 5 (‘very often or always true’).

  • Time spent on mindfulness exercises between the weekly sessions, which was recorded in a daily diary.

Procedure of the Study

• Before MBSR sessions

  • MRI scans of the brain were conducted two weeks before the experimental group’s first MBSR session.

  • 3D models were created by taking pics from 128 sagittal slices of the brain and combining them using computer software.

  • Then, the researchers analysed the models using voxel-based morphometry to measure the concentration of grey matter in the regions of interest (bilateral hippocampi and insulae) and the brain as a whole. 

  • All participants also completed the Five Facets of Mindfulness Questionnaire

• During the eight-week program

  • Sessions → eight, weekly, at the Centre for Mindfulness at the University of Massachusetts Medical School.

  • The participants in the experimental group were given a 45-minute audio recording of guided mindfulness exercises (ex. Body scans, yoga and meditation) to help them complete the exercises at home.

• After the eight MBSR sessions

  • Further MRI scans of the brain were taken two weeks after the last MBSR session for all participants, including the control group, and everyone took the FFMQ again. 

  • Each participant’s two scans were compared using VBM computer software to measure any differences in grey matter concentration and differences in the five facets of mindfulness scores were calculated.

Results of the Study

• Amount of mindfulness practice

  • The MBSR group engaged in an average of 22.6 hours of MBSR exercises. 

  • Standard deviation was 6.3 hours → some participants practiced more than others did.

  • Overall, participants spent around 27 mins practicing the exercises.

  • Most time was spent body scanning → more than twice the time spent on yoga or meditation. 

  • No significant correlation between any of the individual exercises → different people preferred different exercises but doing a lot of one particular exercise did not mean that you also did a lot of the other two.

• Improvements in mindfulness

  • The FFMQ showed that the experimental group demonstrated significant improvements in ‘acting with,’ ‘observing,’ and ‘non-judging’ after MBSR training compared with the control group, but they did not show improvements in ‘describing’ or ‘non -reactivity.’

• Grey matter changes

  • The MBSR group experienced a significant increase in grey matter concentration in their left hippocampus, posterior cingulate cortex, temporoparietal junction and cerebellum compared with the control group.

  • Changes in the cerebellum were observed in two locations; one of these included the brainstem. 

  • As the two groups showed no significant difference in grey matter concentration in these structures before MBSR training, it appears that the differences at eight weeks were due to the MBSR and not pre-existing individual differences.

  • No significant differences were found in grey matter concentration in the insulae before and after the MBSR training. 

  • Changes in grey matter were not correlated with the amount of time spent engaged in mindfulness exercises or changes on the FFMQ. This means that the time spent on mindfulness is more important than how regular you practice.

  • No brain structures showed a decrease in grey matter concentration. But the control group showed decreased grey matter in the posterior cingulate cortex.

Conclusion

• The concentration of grey matter increases in regions in the hippocampus, posterior cingulate cortex (PCC), left temporoparietal junction (TJP) and cerebellum in those who practice an 8-week mindfulness-based stress reduction course (MBSR)

Ethical Issues

• Risk of not protecting participants from harm by not assisting control group participants until at least eight weeks.

Evaluation of the Study

• Strengths

  • The increased external validity of findings derived from longitudinal studies stems from the extended duration, which helps stabilize fluctuating participant variables such as mood, attentiveness, and health, among others, that could influence mindfulness.

  • High amounts of standardisation: for instance, a fixed number of exercises to be performed and fixed total duration- make the study highly replicable, raising reliability.

• Weaknesses

  • Population validity: Lack of generalisability of the sample as they were all similar due to already being enrolled in MBSR courses and having the same level of education.

  • The unknowns regarding the accuracy of the MRI and the lack of objectivity in the interpretations of the data produced decrease the internal validity.

  • The lack of correlation between grey matter and time spent on mindfulness exercise homework shows that the exercises did not directly cause brain changes, which also decreases internal validity.

Issues & Debates (Discussion)

• Application to everyday life: Provides a method to help people with temporoparietal junction (TPJ) impairment, and the two areas of the cerebellum where grey matter changes were observed can be used for emotion regulation and healthy psychological functioning.

• Nature versus Nurture: The biological aspects are highly determined by the processes of nature. However, the study showed that nurture through MBRS can affect those structures and processes.